1. Field of the Invention
This invention relates to devices for protection against the aftermath of frozen water supply systems and particularly to devices for preventing water damage to buildings after frozen water pipes have thawed. It specifically relates to devices for automatically closing water supply lines when freezing conditions occur and keeping them closed during the subsequent thaw.
2. Review of the Prior Art
Power failures during blizzards in northerly climates can cause severe freezing damage to pipes, in spite of good insulation, and devastating water damage to the interiors of unoccupied homes, commercial buildings, and industrial plants during a subsequent thaw. In addition, freezing of water in pipes, causing rupture of the pipes and subsequent damage to buildings by escaping water, is a common difficulty in areas of the world where severe freezing is sufficiently infrequent that plumbing design does not include complete thermal protection.
Devices that depend upon the expansion of water or another substance during freezing thereof, to cause bleeding of water from the system and consequent prevention of freezing within pipes of the system, include U.S. Pat. No. 4,313,452 of Mellard, U.S. Pat. No. 4,784,173 of Carney, and U.S. Pat. No. 4,848,389 of Pirkle. If such bleeding devices fail or if they are not installed, as is commonly the situation in vacation homes, a close-off device is badly needed to shut off the supply of water at the onset of a freeze or at least at the onset of a thaw.
A valve device that shuts off water flow from a main to a water system within a building at the onset of a freeze must be maintained in its closed position during the thaw as well as during the freeze. Valve devices having a latch means for retention of the closure position include U.S. Pat. No. 4,438,777 of Pirkle and U.S. Pat. No. 4,844,412 of Kubozono. The former utilizes wax as its temperature detection medium and is designed for use with locomotives. The latter is designed for oil-filled hydraulic systems and is not directed to the problem of freezing and thawing of water systems.
There is accordingly a need for a failure-safe freeze shutoff or guard valve for homes, commercial buildings, and industrial plants that is automatically operable during freezing weather without manual or electrical operation thereof and that remains in its shutoff position during the subsequent thaw until selectively opened.